The present invention relates to a double wiping female contact and especially to such a contact having spring members which amplify the deflections imposed to magnify the contact pressures developed. Hitherto, many different types of double wiping female contacts have been utilized to develop the high contact pressure necessary for retaining and electrically interfacing with male contacts. Most such contacts consist of a pair of opposing cantilever springs and it would appear that the contact pressures developed thereby could be increased by merely varying the length, width, or thickness of the spring members. However, variations in length are not practical because an increase in contact pressure requires a reduction in length which thereby affects the required length of the male contact. Variations in width are not practical because an increase in contact pressure requires an increase in width and where the female contact is adapted to receive male contacts of either a parallel or a tandem pair, the width of the spring members is limited in magnitude. Generally, this limitation is caused on one side by the center to center distance separating the male contacts of the parallel pair and on the other side by the overall dimensions of the connector body. The contact pressure increases as the thickness of the spring members increases which usually depends on the thickness of the material utilized to fabricate the female contact. Although the thickness of the spring members is relatively unlimited, increases in material thickness are not practical because they are accompanied by increased expense for both raw materials and fabrication. Also, the deflectable range of the spring members below their elastic limit decreases as the material thickness increases and therefore the thickness range of engaging male contacts is reduced.
In some instances the contact pressure has been increased through the use of materials having a very high modulus of elasticity. However, the electrical resistivity of many materials, such as copper, increases as the modulus of elasticity increases and therefore, the current carrying capacity of the contact is decreased by such an approach. Also, materials having a very high modulus of elasticity are usually more costly and more difficult to fabricate.
Various codes and specifications require that female contacts be capable of engagement by male contacts of varying thicknesses and that a specific contact pressure be exerted upon male contacts of minimum thickness after male contacts of maximum thickness have been engaged. These requirements can not be met by many female contacts because the spring members will be deflected beyond their elastic limit when the male contact of maximum thickness is inserted. Such deflections cause a permanent set in the spring members which reduces the contact pressure developed thereafter upon male contacts of minimum thickness.